The present invention relates generally to xe2x80x9cseeingxe2x80x9d through materials. Specifically, the present invention relates to using electromagnetics to xe2x80x9cseexe2x80x9d through materials. Further, the present invention relates to determining the characteristics of other materials in the vicinity of the materials through which the present invention has seen.
There are many examples of the use of electromagnetics (EM) for sensing and measurements. However, this sensing is usually limited by barriers that are conductive electrically or are ferromagnetic. This is the case in EM sensing through steel tanks, pipelines, well casings and the like. There has long been a need for a device that can make metallic and related barriers transparent. Also, there has been a long felt need for a device that can make barriers transparent with respect to sufficient frequencies of EM waves to achieve useful measurements. A brief list of specific applications that would be possible using a technology that can make barriers transparent with respect to sufficient frequencies of EM waves to achieve useful measurements is provided. For example in an oil well, there are many characteristics of the geology that can be determined by EM waves. Particularly, resistivities of the formation, detection of water in an advancing waterfront due to water drives or water reinjection, mapping, near and far field casing cement resistivity, casing corrosion, reservoir mapping, radar for ground penetration, and the like. These EM measurements are usually done in an uncased well. Well casing is typically xc2xd inch thick steel tubing from 5 inches to 9 inches in diameter.
Problem application areas include, for example, the following:
1. Cased well resistivity measurements.
2. Through storage tank liquid level measurements.
3. Through pipeline resistivity measurements.
4. In pipeline corrosion measurements using a xe2x80x9cpig.xe2x80x9d
5. Refinery and tank farm corrosion measurements.
6. Testing for metal permeability as an indication of its quality.
7. Electrical property measurements originating above or in the ground for characteristic measurements of related media.
It is well known that EM energy is absorbed by ferromagnetic materials because the molecules respond to an EM wave and their response requires energy. Ferromagnetic steel casing has a permeability of about 2,000 to 10,000 depending on the steel. The higher the permeability, the greater the absorption of EM energy. On the other hand, non-ferromagnetic materials such as aluminum, copper, stainless steel and air have permeabilities of 1. Transmitting an EM wave through aluminum however is much different than transmitting an EM wave through air Since aluminum is an excellent electrical conductor, in the near field to an electromagnet the magnetic field predominates. The fact that the magnetic field predominates allows the signal to penetrate the material, e.g., aluminum. Both near and far field signals through the aluminum will experience attenuation because the electrical conductivity of the aluminum generates eddy currents that dissipate the electric component of the EM wave and the movement of the field with respect to time. The case of seeing through ferromagnetic materials has been attempted, but has not been successful. See U.S. Pat. No. 5,038,107.
The situation changes dramatically when the aluminum is replaced by a ferromagnetic material, such as for example, carbon steel. The much higher steel permeability readily dissipates even the near magnetic field. However, the physics of the situation allows some room to overcome this limiting situation. As the magnetic field is increased, more and more of the ferromagnetic material""s atoms begin to line up uniformly in response to the magnetic field. If the magnetic field is increased sufficiently, all of the atoms throughout the thickness of the material will align themselves with the magnetic field. This state is called magnetic saturation of the material. During magnetic saturation, the ferromagnetic materials cannot absorb any more EM energy. In this saturation state, the permeability of the material approaches one. Thus in the saturation state, the permeability of the material approaches the permeability of aluminum or air. Naturally, in the case of ferromagnetic materials as with aluminum, it is still an electrical conductor so the electric component of the EM wave is damped to some extent by eddy currents generated in the material. During this full or partial magnetic saturation, the portion of the material that is fully saturated or partially saturated could become fully or partially transparent for the transmission of a second EM wave, The geometry of this partially transparent region is important The term saturation will be used throughout this invention as both fully and partially saturated as with transparency which will mean fully or partially transparent.
It is, therefore, a feature of the present invention to see through materials, ferromagnetic and nonferromagnetic.
Another feature of the present invention to determining the electrical properties of materials in the vicinity of a material that has been seen through.
A feature of the present invention is to provide resistivity measurements through ferromagnetic casing in oil wells.
Another feature of the present invention is to provide resistivity measurements through ferromagnetic tubing and casing simultaneously.
Another feature of the present invention is to provide detection of liquid interfaces in tanks.
Another feature of the present invention is to provide resistivity and sediment detection in refinery tanks and pipes.
Yet another feature of the invention is to provide flow rate and resistivity measurements in pipelines without using hot taps or other intrusive methods.
Still another feature of the present invention is the measurement of outside casing cement conditions from inside casing or tubing.
Another feature of the present invention is to provide logging through casing and tubing in an oil well.
Another feature of the present invention is that it provides non-contacting arrangement with the surface of the associated material.
Still another feature of the present invention is that surface conditions are not important because inductive fields do not require contact and can be done at a distance.
Additional features and advantages of the invention will be set forth in part in the description which follows, and in part will become apparent from the description, or may be learned by practice of the invention. The features and advantages of the invention may be realized by means of the combinations and steps particularly pointed out in the appended claims.
To achieve the foregoing objects, features, and advantages and in accordance with the purpose of the invention as embodied and broadly described herein, a method for creating a transparency in a material comprising the steps of creating a first electromagnetic wave adjacent to the material, saturating the material with the first electromagnetic wave, creating a second electromagnetic wave having a frequency higher than the first electromagnetic wave, engaging the second electromagnetic wave with the material when the material is fully or partially saturated for creating a transparency in the material with respect to the electromagnetic waves. An apparatus for creating a transparency in a material comprising a large coil, a small coil, a switch, a low noise amplifier (LNA), a receiver, a frequency generator, a pulser, at least one or more capacitors and a power source.